The present invention relates to a system for monitoring the pressure of tires in a vehicle. In particular, the invention relates to a tire pressure monitoring system employing pressure sensors/transmitters located in each tire that transmit information to a receiver/controller.
Prior art vehicular systems exist which use pressure sensors/transmitters located in each tire that transmit pressure information to a receiver. Each sensor/transmitter may have an identification code associated therewith which enables the receiver to know which sensor/transmitter the pressure information is received from. The receiver analyzes the pressure information and, in some systems, displays current pressure information to the vehicle's operator via a mounted display. Some systems also contemplate the provision of a warning signal to the operator in the situation where the tire pressure is determined to be low. Such a prior art system is described in U.S. Pat. No. 5,600,301, the disclosure of which is incorporated herein by reference.
U.S. Pat. No. 5,600,301 provides a "learning" method whereby the receiver can learn the identification code associated with each tire sensor/transmitter, as well as the initial tire location associated with each sensor/transmitter. Furthermore, the method enables recalibration to be achieved whereby upon command from the operator, the receiver learns the new tire positions of the sensor/transmitters caused by rotation of the tires for maintenance purposes when the operator signals a learn mode at the drivers console and each tire transmitter is signaled to transmit a ID code in a specific order of wheel location on the vehicle.
However, prior art systems have not addressed the problem of enabling such systems to easily accommodate different "target" pressures of the tires. These target or desired pressures are used for operations such as determining whether or not improper inflation pressures are present and, thus, if a warning signal to the operator should be provided. Such target or desired pressures may vary for a variety of reasons, including different operating characteristics from one vehicle to the next, or may vary in the same vehicle based on the operating terrain or speed of the vehicle. Unfortunately, accommodation of different target pressures in the prior art systems disadvantageously requires the use of discrete pressure-specific part numbers which adds to the complexity of the production, distribution, and servicing of such systems.
Therefore, a methodology is needed whereby the receiver/system can easily learn the target pressure of each tire.